Engine Build - Crankshaft To Cylinder Head - Deck Height

If you're working on a budget, one cost-effective way to build a new engine is to order an engine kit from a mail-order parts company, such as those found in Circle Track.

Begin your engine buildup list by identifying what good parts you already have, such as a cylinder block, a crankshaft and rods. Then, decide what parts you're going to need new, such as a camshaft, lifters, bearings, gaskets and so on. Carefully weigh the cost and hassle between refurbishing stock items and buying new parts. For example, with today's aftermarket offerings, it may be easier and more cost-effective to buy new cylinder heads rather than rebuilding the old units. By the time the old heads have been cleaned, inspected, decked, machined and fitted with new valves and springs, you may have the same amount of money invested as the cost of a new pair of high-flow aftermarket heads.

It's common knowledge that a high compression ratio, a big camshaft and an open-plenum intake manifold combine to deliver high-rpm horsepower. Thus, for a Street Stock concentrate on building an engine that will deliver power throughout a real-world rpm powerband (between 1,500-6,000 rpm, for example). If possible, try to keep the compression ratio between 8.5:1 and 10:1, which will deliver great power without the threat of engine detonation when running on pump gasoline. When choosing a camshaft, it's important to match the camshaft to the engine's cubic-inch size, compression ratio, intake manifold type and exhaust system. For most small-block V-8 engines in the 320-380ci range, you should consider a hydrualic camshaft featuring less than 0.500-inch lift and no more than 280-degrees advertised duration.

If this is your first engine buildup, you may be better off going with an engine kit. Available from numerous mail-order outfits, engine kits are an easy and cost effective way to get a parts combo that is sure to work well. Often, engine kits come with a fully machined cylinder block, reconditioned connecting rods, new pistons with pins, a high-volume oil pump, a heavy-duty timing chain set and a new cam/lifter kit. Plus, the engine kits usually include a complete gasket set and new rod and main bearings. All of the engine parts show up by mail in one package, and then you assemble the engine yourself.

If you're unsure of any aspect of an engine buildup, then get help. Asking a buddy may be the answer for some questions, but if you want to learn how to build an engine before you begin your engine buildup project, then arm yourself with the necessary knowledge. Available from mail-order firms such as Classic Motorbooks (Dept. CC, P.O. Box 1, Osceola, WI 54020, 800/826-6600) are a wide variety of engine-building books that highlight the entire engine-building process in step-by-step sections. For example, if you're building a small-block Chevy V-8, you may want to check out Small Block Chevy Performance, Volume One: 1955 to 1981 or Small Block Chevy Performance, Volume Two: 1982 and Later by John Baechtel. Or, if you've got a VCR, Classic Motorbooks offers a variety of engine-building video tapes.

Before ordering any parts, bring your old engine to a reputable engine machine shop for inspection. Have the machine shop check the cylinder block for cracks, rust or damage that may render the block useless for high-performance use.

Have the machine shop determine the condition of the cylinder bores, particularly if they have been over-bored during an earlier engine rebuild. If the bores are standard (meaning that they have never been over-bored), always try to over-bore the minimum amount needed to deliver a smooth bore--such as 0.030- or 0.040-inch over-bore. Being greedy for additional cubic inches by way of excessively over-boring the cylinders can affect the engine's cooling ability, strength and overall reliability.

If possible, pay a few extra dollars to have the block final-honed using torque plates. The torque plates bolt to the deck of the cylinder block and replicate the clamping pressures delivered when the cylinder heads are torqued in place. The final result of using the torque plates is a smoother, more consistant cylinder bore that promotes improved piston-ring-to-cylinder sealing. In addition, if the deck surface of the cylinder block requires machining to achieve trueness, only deck the block the minimum amount needed. Excessively decking the block can adversely affect valvetrain geometry and intake manifold fit and can also increase the compression ratio too much (which may lead to detonation).

If money allows, have the machine shop align-bore the cylinder-block main caps. The align-bore process delivers a perfectly straight crankshaft centerline within the block. Oftentimes, if the block is not line-bored, uneven clamping pressure will be distributed to the crankshaft--causing it to bind-up slightly as it rotates, which can rob horsepower, cause premature wear or lead to bearing failure.

A simple at-home machining process involves tapping all of the bolt holes on the cylinder block. The tap straightens the bolt hole threads and removes debris from the hole.

Before assembling the engine, always wash the cylinder block, crankshaft and rods with soapy water. Use a bottle brush to clean all of the small holes and galleries in the block.

If money allows, upgrade to brass freeze plugs in place of the stock steel plugs. Apply sealant to the edges of the plug, and then tap it into the cylinder block until the plug's outer edge is flush with the block.

With the crankshaft and rods, always machine the journals the minimum amount needed to achieve a uniform size. If the crankshaft main and rod journals are "standard" size and are in good shape, ask that the journals be cut to 10-10 and no more. A 10-10 crankshaft is one that has been machined down 0.010 inch on the rod and main bearing journals. If your crankshaft is severely worn and/or has been machined during an earlier engine buildup and requires more than 20-20 machining, you should opt for another crankshaft (or a new crank) that is in better condition.

The connecting rods should be examined closely to ensure that there are no casting flaws, cracks and/or excessive wear. Most engine machine shops can Magnaflux the rods, which is a process that can identify cracks that are too small to be seen with your eye. For performance engine applications, insist that the rods be fitted with new high-performance rod bolts and balanced afterward.

Although the machine shop performs most of the labor-intensive, critical measurement machining tasks, there are plenty of low-buck, easy-to-do machining items that your can do yourself. After the cylinder block has been fully machined, use a file and/or grinding wheel to deburr all of the rough edges on the block. In addition, hand sanding and grinding to smooth the inside of the lifter valley will promote better oil flowback and will help prevent sludge buildup. Use a tap/die set to clean out and straighten all of the bolt hole threads in the cylinder block.

Although the cylinder block has been hot-tank-cleaned at the machine shop, you'd be surprised by the amount of crud that will be hiding within the tight spots of the block. Thus, before assembling the engine, thoroughly clean the cylinder block, main caps, crankshaft, rods and pistons with soapy water. Most mail-order parts vendors sell a bottle-brush kit that works great for scrubbing the insides of the camshaft oil gallery holes, the crankshaft journal oiling holes and the coolant passages.

After the engine has been thoroughly cleaned, rinsed and dried, coat the machined surfaces with a rust-preventative like Liquid Wrench, then cover the parts with a plastic bag (such as a garbage bag) to prevent dust and dirt from accumulating on the parts. If you build the engine in steps, be sure to cover the engine with the plastic bag each time you stop working for the day.

The outside of the cylinder block should be painted to prevent it from rusting. Apply a coating of primer to the bare metal surface of the block first, then apply the final-coat paint. To prevent the primer/paint from burning off, use a high-temp paint that is safe for temperatures up to about 550 degrees F. Be sure to mask off any portions of the block that you do not want painted (such as the cylinder head deck surface). In addition, to further aid in oil flowback, you may wish to paint areas like the lifter valley with a high-heat, oil-resistant paint such as that offered by Rustoleum(R).

Always install new freeze plugs (also called frost plugs or Welch plugs) in the cylinder block: Don't try to reuse the old plugs. Moreover, although steel freeze plugs are standard-issue from the factory, we recommend upgrading to brass freeze plugs that won't rust out. The brass plugs install the same way as the steel plugs and cost only a few dollars more.

The key to a successful short-block assembly is attention to detail. Every aspect of the short-block reciprocating assembly is designed to work with specific clearance tolerances. If the wrong bearing size is used or if the bearing is installed incorrectly, metal-to-metal contact will occur, resulting in engine failure. Even if the box indicates that the bearing is a certain size/thickness, use gauging plastic to measure main and rod bearing clearance.

Install the main bearing in the cylinder block dry. Then, add a coating of assembly lube to the top of the bearing.

In most cases, main journal bearings should be installed into the cylinder block dry, and then have a slathering of assembly lube applied to the bearing top surface that directly faces the crankshaft journal. Apply assembly lube to the crankshaft main journals before installing the crankshaft into the block. Carefully lower the crankshaft into the block main journal saddles while paying keen attention to keeping the crankshaft level to the cylinder block. Do not set one end of the crank into place and then lower the other end into position--this can distort and/or damage the main bearings.

Install the main caps, and thread in the main bolts finger tight. Then, torque the bolts incrementally, in sequence until the final torque spec is achieved. Afterward, rotate the crankshaft slowly to verify that no binding occurs.

Before installing the rod/piston combo in the cylinder bore, wipe the cylinder walls with a lint-free towel. Then, apply a light coating of assembly lube to the cylinder walls. Install the piston rings per manufacturers' recommendations. Phase piston ring gaps opposite from each other to help deter cylinder pressure blow-by. If the pistons have domes or machined- or cast-in valve reliefs, make sure that the piston is installed with proper orientation to prevent piston-to-head or -valve contact.

To install the pistons within the block, use a quality ring compressor and the wooden end of a hammer to tap the piston into the cylinder bore. Tap the piston into position slowly to prevent the rod bearing from popping out of the rod. To prevent the sharp ends of the rod bolts from gouging the cylinder bore and/or the crankshaft main journal, slip on two small pieces of rubber hose over the ends of the rod bolts. Afterward, remove the rubber line, and install the rod cap. Thread on the rod cap bolts, and tighten until snug. Install the other rod/piston combo that is paired on the same rod journal as the other rod. Once both rods that share the same crankshaft rod journal are in place, torque the bolts incrementally to the proper torque spec. Rotate the engine to verify that no binding or interference occurs. If rotation is fine, then begin installing the rod/piston combo on the next cylinder. Once all of the rods have been installed and torqued to spec, check to be sure there is enough rod side clearance.

Carefully set the crankshaft into place making sure not to damage the main bearings. If you've opted to install main studs in place of the stock main bolts, add main bolt covers (or pieces of rubber hose) to the ends of the bolts to prevent gouging the crankshaft journals.

A few pieces of rubber hose over the ends of the rod bolts help prevent scratches on the cylinder walls and/or the crankshaft rod journal.

Installing the camshaft is a fairly simple task. With a new engine, always install new cam bearings. Because cam bearings are tricky to install, we recommend having them installed at the machine shop by a skilled professional who has the proper bearing-install tool.

Apply a coating of assembly lube to the cam bearing surfaces as well as to the camshaft journals. Then, apply a generous slathering of cam lube (which is usually supplied with the camshaft) to each of the cam lobes. The cam lube prevents the cam lobes from going flat (destroying themselves) upon engine break-in. Because a camshaft and lifters wear into a specific pattern, never reuse old lifters with a new camshaft. In addition, if you ever have to remove the lifters, be sure to re-install them in the same lifter bore from where they originally came.

Because timing chains stretch (which negatively affects engine performance), reusing the old timing chain set would be foolish. We recommend upgrading to a rollerized, double-row timing chain matched with steel gears. Many stock timing chains are a single-row design that use cast iron or plastic gears that are not well noted for high-performance use. When the timing gears are installed, be sure to align the two dots so that they are phased parallel, directly next to each other. If the dots are not aligned, the camshaft will be improperly phased, which will likely lead to piston-to-valve interference and/or engine failure.

As with the camshaft, be sure to apply cam lube to the sides and bottom of the lifters.

Setting the proper valvetrain lash with a hydraulic camshaft on those engines that utilize an adjustable valvetrain is extremely important--and easy to perform. With the cylinder head bolted (and torqued) into place, install the pushrods and rocker arms so that they align properly. Rotate the camshaft so that the lifter to be adjusted is on the base circle portion of the cam. Then, while slowly spinning the pushrod, tighten the rocker arm nut until you feel a slight amount of drag. When this occurs, you have reached "zero lash." At this point, tighten the rocker arm nut 3/4 to one turn further.

With a hydraulic camshaft, tighten the rocker arm nut until "zero lash," and then tighten the nut one additional turn.

With a solid lifter camshaft, rotate the cam so the lifter is on the base circle of the cam. Then, insert a feeler gauge (proper gauge thickness is determined by the cam manufacturer's recommendation--usually between 0.010-0.030 inch) between the tip of the valve stem and the lower edge of the rocker arm. Slowly tighten the rocker arm nut until you can barely insert the feeler gauge of the correct size.

Degreeing a camshaft verifies the grind specifications that the cam is supposed to deliver. Cam specs may vary due to human error, improper grinding machine calibration or even because the cam was installed in the wrong box (with the incorrect label). Then again, using a degree wheel will allow you to advance or retard the camshaft timing (or camshaft phasing) that will alter horsepower at different rpm ranges. Usually, advancing the cam will move the power band down in rpm, and retarding the cam will move the power up in rpm.

To degree a camshaft, start by using a dial indicator (A) to determine when the No. 1 piston is at Top Dead Center (TDC). Then, install the degree wheel (B) on to the end of the crankshaft. Install the cam degree pointer (C) so that it aligns with the "zero" mark on the degree wheel.

Install a dial indicator into the lifter bore (this dial indicator is held snugly in the lifter bore by O-rings mounted on the indicator shaft.) Press the dial indicator down into the lifter bore until it contacts the base circle of the camshaft. Then, zero the dial indicator. As the engine is rotated through its firing order, the dial indicator will note how much lift the camshaft is delivering.

To degree the cam using the intake centerline method, begin by rotating the engine clockwise until the dial indicator reads about 0.025-inch before maximum camshaft lobe lift. Record this location on the degree wheel (83 degrees, for example--arrow A). Continue rotating the engine in the same direction past maximum lobe lift until the pointer is at the original checkpoint. Mark the degree wheel (140.5 degrees--arrow B). Add the two readings, and divide by two. The result is the intake centerline (111.75 degrees--arrow C).

If, according to the camshaft specifications card the intake centerline for the cam is supposed to be 109 degrees, then you must advance the cam 3 degrees. If checking the cam using the 0.050-inch opening-and-closing-points method, rotate the engine clockwise until reaching the 0.050-inch check points, compare the numbers observed on the degree wheel at the proper check points to the numbers listed on the timing card, write down the difference in terms of degrees advanced (early) or retarded (late), and average the results to determine if the cam needs to be advanced or retarded.

Most V-8 engines work best with a free-flowing aluminum intake manifold and a single four-barrel carburetor. Although high-rise intake manifolds deliver great high-rpm revibility, they usually deliver poor low-rpm response. Try sticking with a four-barrel carb in the 600- to 750-cfm range.

A high-volume fuel pump is a smart upgrade for an engine fitted with a performance carburetor and intake manifold. Most aftermarket mechanical fuel pumps are direct bolt-ons that will deliver the proper fuel volume and pressure during the entire rpm range of the engine. Stock fuel pumps usually can't feed hi-po engines properly, thus resulting in poor performance.

If there is one part of your engine buildup on which to spend a few extra bucks, it's the gaskets. Always buy high-performance gaskets from a reputable manufacturer.

When it comes to cylinder sealing, it is a good idea to upgrade to single-moly piston rings. Worn cylinder head valve guides should be replaced (preferably with bronze guides) to help keep the valve face centered on the valve seat, which better seals the cylinder. Valve seals play an important role in cylinder sealing because they keep oil from entering the combustion chamber, especially on the intake valve where oil can negatively affect combustion. OEM valve seals are usually good enough for most applications, but Teflon(R) P.C.-type seals provide improved sealing. Never cut corners on an engine buildup by using cheap head gaskets. To achieve optimum cylinder sealing. Use top-quality gaskets such as offered from Fel-Pro, McCord, ROL and Ultra-Seal.

Traditional piston rings do a good job of sealing a mild engine, but insist on top quality moly rings for performance engine applications.

All parts of an engine are designed to run within a specific clearance of neighboring parts. If the clearances are too tight, excessive wear will occur. If clearances are too loose, excessive play will occur, thus resulting in additional wear and/or part-to-part contact that can lead to engine failure. But, there is no one, general clearance that covers all engine parts. Proper main bearing clearances are different from optimum rod side clearance, and piston-to-valve clearance differs from crank endplay. But, all clearances are extremely important in ensuring a long-lasting, reliable performance engine.

Using gauging plastic is one of the most popular methods of determining bearing clearance. To measure the crankshaft main journal bearing clearance, break off a small pieces of the gaging plastic, and place one strand on each journal (arrow A). Then, install the bearing main caps, and torque the main cap bolts to spec. Afterward, remove the main caps. Use the measurement table printed on the gauging plastic package to measure the compressed portion of the gauging plastic (arrow B). The measurement is your bearing clearance. If clearance is too tight or excessive, different bearings will be needed, or the crankshaft has been machined incorrectly.